Move rootUserSelectAllForNode() to EditingStrategy template class from PositionAlgorithm template cl

Move rootUserSelectAllForNode() to EditingStrategy template class from PositionAlgorithm template class

This patch moves |rootUserSelectAllForNode()| to |EditingStrategy| template
class from |PositionAlgorithm| template class to simplify |PositionAlgorithm|
class for improving code health, since an implementation of
|rootUserSelectAllForNode()| is independent from |PositionAlgorithm|.

BUG=518738
TEST=n/a; no behavior changes

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=200899

[yosin_UTC9, 2015-08-20 08:58:31]

yosin@chromium.org changed reviewers:
+ hajimehoshi@chromium.org, yoichio@chromium.org

[yosin_UTC9, 2015-08-20 08:58:31]

PTAL

[hajimehoshi, 2015-08-20 11:10:45]

lgtm

[yosin_UTC9, 2015-08-20 11:21:55]

The CQ bit was checked by yosin@chromium.org

[commit-bot: I haz the power, 2015-08-20 11:22:15]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1287053007/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1287053007/1

[commit-bot: I haz the power, 2015-08-20 12:25:08]

Committed patchset #1 (id:1) as
https://src.chromium.org/viewvc/blink?view=rev&revision=200899